(1) Field of the Invention
The present invention relates to an electrically driven power steering system and a control apparatus for the electrically driven power steering system.
(2) Description of Related Art
In general, in an electrically driven power steering system, a motor current is feedback controlled using motor phase currents. Previously proposed methods of detecting the three phase currents for respective phases using a single current sensor are exemplified in two Japanese Patent Application First Publications No. 2001-327173 published on Nov. 22, 2001 and No. 2008-131770 published on Jun. 5, 2008. In the above-described two Japanese Patent Application First Publications, when voltage command values of three phases are assumed to be a maximum phase, a middle phase, and a minimum phase in a magnitude (decreasing) order, such a phase correction that phases of PWM pulses of the maximum phase and the minimum phase with respect to a PWM switching timing of the middle phase are shifted secures a time duration required to detect the phase currents of the respective three phases.